RoR编辑嵌套表中的联接表的值

Question

I am a noob on Ror. Been looking for my problem answers for 3 days now, I have been looking for the answers but can't find one with my specific problem. ( I even found it hard to write the right title)

So I have been trying to build a nested form in RoR. I have a simple order form that enable users to specify the quantity they ordered in that form. The form will only store the value into the database if the quantity text field is not empty.

The Order form is simply look like this:

I am storing the quantity data into the join table between order and inventory which has many to many relationship through Inventory_orders table. now in the Inventory_orders table instead of only having orders_id and inventories_id , I also add the quantity column.

now I have been able to get the form working with the code below: Controller:

def new
    @order = Order.new
    @customer = Customer.all
    @inventories_list = Inventory.all 
    @inventory_order = @order.inventory_orders.build
  end

  def create

    @order = Order.new(order_params)
    @inventories_list = Inventory.all #controller can call any model

    respond_to do |format|
      if @order.save
        format.html { redirect_to @order, notice: 'Order was successfully created.' }
        format.json { render :show, status: :created, location: @order }
      else
        format.html { render :new }
        format.json { render json: @order.errors, status: :unprocessable_entity }
      end
    end
  end

 def order_params
      params.require(:order).permit(:customer_id, :order_ids => [],:inventory_orders_attributes => [:id, :quantity, :inventory_id ])
    end

View:

<%= form_for(@order) do |f| %>
<div id = “Main_Container">
*** Some Code  ***
                <table id = "inventory_table">
                  <tr>
                    <td class = "prodCodeTitle"><h3>Prod Code</h3></td>
                    <td class = "prodResult"><h3>Quantity</h3></td>
                    <td class = "prodResult"><h3>Size</h3></td>
                    <td class = "prodResult"><h3>Price</h3></td>
                  </tr>

//Here display all the inventories list 
 <% @inventories_list.each do |t| %>
                  <tr>

                    <td class ="prodResult"><%= link_to t.pName, inventory_path(t), :remote => true %></td>
                    <td class = “prodResult">
        //nested form for the join table
                      <%= f.fields_for :inventory_orders do |qty| %>
                         <%= qty.hidden_field :inventory_id , value: t.id %>
                         <%= qty.number_field :quantity %>
                     <%end%>
                    </td>
                    <td class = "prodResult"><%= t.pMeter %></td>
                    <td class = "prodResult"><%= t.pSellPrice %></td>

                  </tr>
                    <% end %>
             *** Some Code***
<% end %>

Model:

class Order < ActiveRecord::Base
    belongs_to :customer
    has_many :inventory_orders
    has_many :inventories, through: :inventory_orders
    validates :customer_id, :presence => true

    accepts_nested_attributes_for :inventory_orders, :reject_if => lambda { |a| a[:quantity].blank?}

end

class InventoryOrder < ActiveRecord::Base
    belongs_to :inventory
    belongs_to :order


    validates :quantity, :presence => true
end

Now when creating new Orders form , the application works and store the data that I want in the inventory_orders table.

The problem occurs when I try to edit the form. When trying to click on edit button I get this output in my View file:

for example this is what I Input into the form:

when I try to edit the form this is what I get:

this is my controller for edit:

def edit
    @order = Order.find(params[:id])
    @customer = Customer.all
    @inventories_list = Inventory.all

 end

I have been looking at the psql database schema by manual do sql query as follow:

select * from inventory_orders where inventory_orders.order_id = 63;

and get this as result:

now it seems that the fields_for Inventory_orders get the number of rows returned , but I don't get why all the quantity also get displayed 4 times for each product. Also how can I ensure that when I try to edit quantity for product “aaa” it will only display one number_field with what users has input before.

Sorry for the long post,otherwise I am not sure how to clearly convey my meaning.

EDITED this to show my Inventory Model:

Class Inventory < ActiveRecord::Base
  has_many :inventory_orders
  has_many :orders, through: :inventory_orders
end

Answer 1

You need to use the following:

//Here display all the inventories list 
 <% @inventories_list.each do |t| %>
    <%= link_to t.pName, inventory_path(t), :remote => true %>
    <%= f.fields_for :inventory_orders, t do |qty| %>
            <%= qty.hidden_field :inventory_id , value: t.id %>
            <%= qty.number_field :quantity %>
    <% end %>
    <%= t.pMeter %>
    <%= t.pSellPrice %
<% end %>

The issue is that since f.fields_for populates a form based on the built associated objects, if you're passing 4 fully constructed objects through the edit action, fields_for is going to populate all of them each time.

What you need is to use the instance of the associated data .

---

I think your code could be improved a lot:

#app/controllers/orders_controller.rb
class OrdersController < ApplicationController
    def new
        @order = Order.new
        @inventory = Inventory.all 
        @inventory_order = @order.inventory_orders.build
    end

    def edit
        @order = Order.find params[:id]
        @inventory = Inventory.all
    end
end

#app/views/orders/new.html.erb
<%= form_for @order do |f| %>
    <% @inventory.each do |inventory| %>
       <%= f.fields_for :inventory_orders, item do |item| %>
          <%= item.text_field :quantity %>
       <% end %>
    <% end %>
    <%= f.submit %>
<% end %>

#app/views/orders/edit.html.erb
<%= form_for @order do |f| %>
   <%= f.fields_for @order.inventory_orders do |item| %>
       <%= item.text_field :quantity %>
   <% end %>
   <%= f.submit %>
<% end %>